The thing is really Arianespace don't know exact dates. The most...

The thing is really Arianespace don't know exact dates. The most you can get out of them is a month forward.
http://www.arianespace.com/news/mission-status.asp


Obviously J2 has been ready to go for sometime now so I think it was more a matter of finding a suitable launch partner also ready to go. From what I have followed there seem to have been a number of potential partners that have been delayed for one reason or another over the last year or so.

Measat 3C is a hosted payload aboard NWT's Jabiru 1 - much the same as NWT's Jabiru 2 is actually a hosted payload on Measats 3B. Both are going into the same slot position.

Good quote (and cheers for posting these articles):
"For Measat-3C we collaborate with an Australian company. Works are on schedule and thus we are confident to launch it next year to provide better and upgraded connectivity to Malaysians as well as Africa, India and across the region,” he said."